An imaging sensor system forms an image of a target on an imaging sensor. The imaging sensor converts the incident light image to electrical or optical signals for further processing such as pattern recognition functions. The imaging sensor system is distinct from a non-imaging sensor system, which reacts to the presence of the target but does not form an image of the target.
One potential application of imaging sensor systems is the detection of buried anti-personnel or anti-vehicle explosive mines. Such explosive mines, if undetected, may pose a hazard long after an area is otherwise thought to be safe for use. Once detected, such explosive mines may be neutralized or avoided, in the course of preparing the mined area for subsequent use.
The buried explosive mines may be detected based upon the spectral differences in the thermal emissivities of disturbed and undisturbed soils. One technique based upon this principle is to image the area being searched in two infrared wavelengths. The images are mathematically processed using appropriate algorithms to establish the presence of disturbed soil, which in turn suggests the possible presence of a buried explosive mine.
One approach to performing this explosive-mine detection based upon thermal emissivity differences requires the optical alignment of multiple sets of optics and the calibration of the imaging sensors. Such alignment and calibration are difficult to perform initially, and it is difficult to keep the multiple sets of optics aligned and calibrated during service. Further, the available apparatus is bulky and expensive.
There is a need for an improved approach to the detection of buried explosive mines using the differences in the emissivities of disturbed and undisturbed soils, and for other applications that image light in two different spectral bands. The present invention fulfills this need, and further provides related advantages.